The present invention relates to a surveying instrument and a method for detecting light of fan shaped laser beam, as well as to a surveying system comprising the surveying instrument and to a light emitting device emitting the fan shaped laser beam.
Various kinds of surveying instruments are used for measuring distances and angles between objects. Hereby, several conventional surveying instruments use a laser source to measure the distance to or the position of an object by performing an electro-optical measurement.
When measuring the distance or position, the operator has to verify that the laser beam of the laser source actually impinges on the object at a desired position. However, a laser spot, e.g. impinging on a wall, is usually quite small, and in Z-mode at a far distance a user may have difficulty finding the laser spot with the naked eye or with a conventional photodetector. Additionally, the intensity of the laser beam decreases over the distance so that the intensity of backscatter light from the wall further decreases.
Therefore, due to the small size of the laser spot and the distance from the laser source, it may be cumbersome and sometimes even impossible to find the laser spot with the eye or by moving around a photodetector in a target area.
Furthermore, finding a small laser spot gets even more complicated under field conditions, such as snow, rain and wind, in which a quick and secure detection is desired.
Therefore, the need arises for a surveying instrument and method enabling to find a spot of a laser beam easier and quicker.